To simply answer your question, there is no way to smooth out wrinkles or creases on Glassine paper. As you can see from the sheets you currently have, glassine is a smooth, thin and hard sheet and is susceptible to creasing. Unfortunately due to these characteristics there is no way to get the marks left out of the sheet.

Generally Glassine is used as an interleaving sheet between fine art prints and reproductions. What applications are you using with it?